WO2020249321A1

WO2020249321A1 - Apparatus for electrically contacting the control/evaluation electronics of a field device

Info

Publication number: WO2020249321A1
Application number: PCT/EP2020/062527
Authority: WO
Inventors: Michael Dötsch; Robert Schmidt; Ralf Leisinger
Original assignee: Endress+Hauser SE+Co. KG
Priority date: 2019-06-13
Filing date: 2020-05-06
Publication date: 2020-12-17
Also published as: US20220247103A1; CN113994544A; EP3984099A1; CN113994544B; US11824287B2; DE102019116154A1

Abstract

The invention relates to an apparatus for electrically contacting the control/evaluation electronics (1) of a field device in automation technology with an external energy supply and/or control, wherein: the control/evaluation electronics (1) of the field device are arranged on a circuit board (2); at least one terminal housing (3) is provided in which a plurality of electrical connector terminals (4), arranged adjacent to one another, are provided; the electrical connector terminals (4) each serve to receive an electrical connection element (5); the electrical connection elements (5) are each mechanically and electrically connected by means of a solder pad (6) to the circuit board (2); and between each pair of solder pads (6) in the circuit board (2), recesses (7) are provided that are designed such that the length of the creepage distance between the solder pads (6) meets a predefined ignition protection class.

Description

Device for electrically contacting the

Control / evaluation electronics of a field device

The invention relates to a device for electrically contacting the control / evaluation electronics of a field device in automation technology with an external energy supply and / or control.

In process automation as well as in production automation, field devices are often used to record and / or influence physical, chemical or biological process variables. Measuring devices are used to record the process variables. These will

Used for example for pressure and temperature measurement, conductivity measurement, flow measurement, pH measurement, level measurement, etc. and record the corresponding process variables pressure, temperature,

Conductivity, pH value, level, flow, etc. Actuator systems are used to influence the process variables. Examples of actuators are pumps or valves that can influence the flow of a liquid in a pipe or the level in a container. In addition to the aforementioned measuring devices and actuators, field devices also include remote I / Os, radio adapters or, in general, devices that are arranged on the field level. Generally speaking, field devices are devices that are used in the vicinity of the process or plant and that supply or process information relevant to the process or plant.

To enable field devices of automation technology also in

In order to be able to use areas at risk of gas explosions, the electrical components of the field devices must have the appropriate explosion protection type, e.g. the type of protection "increased safety Ex e" must be designed. Subgroups of this standard apply to defined electrical components. For example, the Ex-ec (DIN EN 60079-7) standard applies to connections, conductors, windings, lamps and batteries, including semiconductors or

Electrolytic capacitors. In this standard, among other things, defines how large the distance between the terminals on a circuit board is

arranged control / evaluation electronics of a field device must be if the field device is connected to a mains voltage of 230V AC should. If the distance specified in the standard is observed

ensures that no leakage currents flow between the connection terminals, thereby avoiding a short circuit with sparking. If the required creepage distance is observed, in

A risk of explosion is excluded in areas with a risk of gas explosion.

The invention is based on the object of providing a device for making electrical contact with the control / evaluation electronics of a field device

To propose automation technology with an external power supply and / or control that can be used for the hazardous area.

The object is achieved by a device for electrically contacting the control / evaluation electronics of a field device in automation technology with an external power supply and / or controller, the control / evaluation electronics of the field device being arranged on a circuit card, with at least one terminal housing being provided in the several

electrical connection terminals arranged next to one another are provided, the electrical connection terminals each serving to accommodate an electrical connection element, the electrical

Connection elements are mechanically and electrically connected to the circuit card via a soldering pad, and recesses are provided between two soldering pads in the circuit board, which are designed so that the length of the creepage distance between the soldering pads fulfills a specified ignition protection type. An embodiment of the solution according to the invention that is easy to implement in terms of production engineering provides that the recesses are slots that are milled into the circuit board.

As a result of the invention, as well as the embodiment described above, an air gap is also formed on the direct connection line between two connection terminals - that is, between two adjacent soldering pads of the connection terminals that are arranged on the circuit card - in addition to the creepage distance on the circuit card. Since air has a higher resistance value than the circuit board, the creepage distance becomes due to the intervening Air gap extended. The same naturally also applies to the extension of the creepage distance on the circuit board, since it leads around the recesses or the slots. Depending on the width of the air gap or the width and length of the recesses, the invention enables a specified type of protection to be implemented without the distance between two connection terminals having to be increased. This has the advantage that, firstly, the dimensioning can be kept small - which is the progressive

Miniaturization of the printed circuit boards accommodates - and the same

Standard components, here e.g. one and the same connector can be used for several explosion protection variants of a field device.

According to an advantageous embodiment of the device according to the invention, an elongated component with two opposing surfaces is proposed, with webs being provided on one of the two surfaces of the elongated component which are arranged and designed so that they engage or can be inserted into the corresponding recesses of the circuit card are. It goes without saying that the elongate component is made of a non-conductive material. This configuration is preferably used when the circuit card with the connection terminals is aligned essentially perpendicular to the bottom surface of a field device housing and the circuit card is filled with a potting compound made of non-conductive material up to the level of the soldering pads or the connection terminals. A suitable potting usually has a tracking resistance - characterized by the Comparative Tracking Index CTI - of preferably greater than 500. The material from which the elongated component is made also has a comparable value.

The creepage resistance characterizes the insulation strength of the surface (creepage distance) of insulating materials. It defines the maximum leakage current that can occur under standardized test conditions in a defined test arrangement. While conventional circuit card materials have a CTI of less than 250, for example 125, plastics used as potting compounds, such as polyethylene, polyester resin, PTFE or PBT, have a CTI of preferably 500-600. The higher the CTI of the materials or material used , the smaller the distance between two can be Electronic components, here the connection terminals, must be designed to meet a specified type of protection.

If the field device housing is potted up to the level of the

Recesses / slots in the printed circuit card standing vertically in the field device housing are filled, there is a risk that the through the

Recesses as a result of the creepage distance through air reached high

Leakage current resistance is reduced. This is the case when material of the potting compound penetrates into the recesses / slots. The reason is the lower creep resistance of the potting compound compared to the creep resistance of air.

The presence of potting compound within the recesses is quite likely when the printed circuit board is potted. The dosing amount of potting compound as well as the dimensioning of the interior of the field device housing to be filled are subject to certain fluctuations. Since all electrical connections / soldering pads and electrical components of the circuit board should always be protected by the encapsulation, the dosage must be at a determined upper limit. Due to the manufacturing and

Dosing errors cannot be ruled out that the potting will more or less fill the recesses, thereby reducing the creepage resistance previously achieved to meet the specified ignition protection type.

This unacceptable deficiency can be eliminated by inserting the elongated component, since the direct creepage distance between two adjacent soldering pads is through the cutouts / slots

protruding webs is extended. It goes without saying that the length of the webs is chosen so that the webs sit as precisely as possible in the recesses.

A further development provides that on the surface of the elongated

Component that carries the webs, at least one stop support is provided to rest on the circuit board. The stop support is designed so that the surface of the elongated component that carries the webs of the facing surface of the circuit card has a defined distance. Furthermore, the height of the webs is dimensioned such that the webs protrude from the recesses to a defined extent over the circuit board surface. The creepage distance between two adjacent soldering pads of the connection terminals thus extends from a soldering pad over the circuit board, the possibly existing potting in the recess, the web of the elongated component protruding from the circuit board, the possibly existing potting in the recess and the circuit board up to neighboring

Solder pad. The required creepage distance to meet the respective type of protection can be achieved by adjusting the height of the webs accordingly. The height of the webs protruding from the circuit board is dimensioned in such a way that the necessary creepage distance is available to achieve the desired type of protection. Alternatively or in addition to the aforementioned embodiment of the

The device according to the invention is at least one of the webs in a region adjoining the surface of the elongate component as

Stop support for the printed circuit card is formed so that the surface of the elongated component that carries the webs is at a defined distance from the facing surface of the printed circuit card. Whether one or more stop supports are provided depends on the length expansion of the elongated element and thus on the number of connection terminals.

An advantageous embodiment of the device according to the invention suggests that the two webs arranged in the end regions of the elongated component are each designed as latching means, in particular as snap hooks, in the web region that protrudes into the corresponding recess, such that the elongated component is attached to the circuit board , preferably releasable, fixable.

According to the invention, the width and length of the recesses are designed so that the creepage distance on the printed circuit board around a recess is sufficient to maintain the specified type of protection.

In addition, it is proposed that the height of the webs is designed so that the creepage distance along the webs to maintain the specified Type of protection is sufficient. The height of the webs is designed in particular so that even in the presence of a material - eg

Potting compound - the creepage distance along the webs in the recesses is sufficient to maintain the specified type of protection. The

The presence of potting compound in the recesses, which are normally filled with air, cannot be ruled out if the circuit card is in a field device housing and there in an upright position - i.e. in the

Essentially vertical to the bottom surface of the field device housing - with

Potting compound is potted. The reasons for this have already been given

mentioned previous place.

It should be mentioned that the elongated component with webs,

Snap hooks and stop supports made of a non-conductive material, flexible material, preferably plastic.

The type of protection to be complied with is preferably the type of protection Ex ec - increased safety. This makes it possible to use the field devices in an environment with a risk of gas explosion, as it is ensured that no short circuit occurs between the connection terminals when energy is supplied or in the event of a fault.

The invention is explained in more detail with reference to the following figures. It shows:

1: a perspective view of the top of a circuit card with an embodiment of the device according to the invention,

FIG. 2: a perspective partial view of the underside of the printed circuit board shown in FIG. 1,

3: a perspective view of an elongated component suitable for the solution according to the invention,

4: a longitudinal section through a field device housing with an integrated circuit card and Fig. 5: a longitudinal section through the in fig. 4 shown field device housing with encapsulated circuit board.

1 shows a perspective view of the top of a printed circuit card 2 with an embodiment of the device according to the invention for electrically contacting the control / evaluation electronics 1 of a field device (not shown) of automation technology with an external one

Energy supply and / or control (not shown). FIG. 2 shows a perspective partial view of the corresponding underside of the printed circuit card 2. A plurality of electrical components 13 are arranged on the printed circuit card 2, the specific configuration of which is in connection with FIG

Invention, however, is irrelevant. FIG. 3 shows a perspective view of an elongate component, as it can be used in the embodiment shown in FIGS. 1 and 2.

The control / evaluation electronics 1 of the field device are arranged on a printed circuit card 2. For connection to the power supply and / or control, a multi-part terminal housing 3 is provided, in which several electrical connection terminals 4 arranged next to one another are provided. The electrical connection terminals 4 are used to accommodate an electrical connection element 5. The electrical connection elements 5 are each via a soldering pad or an electrical connection with the

Circuit board 2 mechanically and electrically connected. Recesses 7 are provided in the circuit card 2 between two adjacent or adjacent soldering pads 6. The recesses 7 are preferred as

Designed slots that are milled into the circuit board 2. The recesses 7 or the slots are dimensioned in such a way that the length of the creepage distance between two adjacent soldering pads 6 fulfills a predetermined type of protection.

In order to use the previously described circuit board 2 also a higher

To be able to implement the type of protection, an elongated component 8 is provided. The elongated component 8 has two each other

opposing surfaces, with several vertically oriented webs 9 on one of the two surfaces of the elongate component 8 are provided. These are arranged and designed in such a way that they engage or respectively engage in the corresponding recesses 7 of the circuit board 2

are insertable. The elongate component 8 is preferably releasably connectable to the printed circuit card 2. In particular, for this purpose the elongate component 8 has a flexible snap hook 11 in each of its end regions, which is guided through the corresponding recess 7 and engages on the surface of the printed circuit card 2. The length of the recesses 7 corresponds precisely to the length of the webs 9, while the width of the webs 9 is smaller than the width of the recesses 7.

To ensure that the webs 9 protrude in the assembled state with a defined height above the circuit board 2, is next to

Stop surfaces 12 are provided on the snap hook 11 at least one stop support 10 with a stop surface 12. Additionally or alternatively, at least one of the webs 9 can also be designed in such a way that it has a stop support 10. The stop surfaces 12 of the snap hooks 11 and the stop surface 12 of the stop support (s) 10 rest on the two opposite surfaces of the printed circuit board 2 when the elongate component 8 is mounted. The elongated component 8 is securely fixed to the circuit card 2 via the aforementioned opposing stop surfaces 12.

The surface of the elongated component 8, which carries the webs 9, is at a defined distance from the facing surface of the printed circuit card 2. Consequently, it is also ensured that the webs 9 protrude beyond the circuit card 2 with a defined height ha.

The width b and the length I of the recesses 7 are designed according to the invention in such a way that the creepage distance on the printed circuit card 2 around a respective web 9 is sufficient to maintain the specified type of protection.

4 shows a longitudinal section through a field device housing 15 with a vertically integrated circuit card 2. In FIG. 5, the field device housing 15 is filled with a potting compound 14 up to the solid line. As already mentioned, on the surface of the elongated component 8 on which the webs 9 are arranged, at least one stop support 10 is provided to rest on the circuit board 2. The stop support 10 is designed in such a way that the surface of the elongate component 8, which carries the webs 9, is at a defined distance from the facing surface of the printed circuit card 2. Furthermore, the height h of the webs 9 is dimensioned so that they are mounted in the

State with a defined dimension ha protrude over the opposite surface of the circuit board 2. The creepage distance between two adjacent soldering pads 6 of the connection terminals 3 thus extends from a soldering pad 6 over the circuit board 2, the corresponding potting 14 in the recess 7 to the web 9, the area of the web 9 protruding from the circuit board 2, the corresponding potting 14 in the recess 7 and the circuit card 2 up to the adjacent soldering pad 6. Due to the design of the elongated component 8 described above, the height ha of the webs 9 protruding from the circuit card 2 can be designed so that the desired type of protection is implemented.

The type of protection to be complied with is preferably the type of protection Ex ec - increased safety. This makes it possible to use the field devices in an environment at risk of gas explosions, since it is ensured that no short circuit occurs between the connection terminals 4.

List of reference symbols

1 control and / or evaluation electronics

2 circuit board

3 terminal housing

4 connection terminal

5 electrical connector

6 Lödpad or electrical connection point on the circuit board

7 recess or slot

8 elongated component

9 bridge

10 system support

1 1 snap hook / flexible retaining element

12 Stop surface for circuit board

13 electrical component

14 Potting / Potting Compound

15 field device housing

Claims

1. Device for making electrical contact between the control / evaluation electronics (1) of a field device in automation technology and an external one

Energy supply and / or control, the control / evaluation electronics (1) of the field device being arranged on a printed circuit card (2), at least one terminal housing (3) being provided in which several electrical connection terminals (4) arranged next to one another are provided, with the electrical connection terminals (4) each serve to accommodate an electrical connection element (5), the electrical

Connecting elements (5) are mechanically and electrically connected to the circuit card (2) via a soldering pad (6) each, and recesses (7) are provided between two soldering pads (6) in the circuit card (2), which are designed in such a way that that the length of the creepage distance between the soldering pads (6) meets a specified type of protection.

2. Device according to claim 1,

wherein the recesses (7) are slots that are milled into the circuit board (2).

3. Device according to claim 1 or 2,

wherein an elongate component (8) is provided with two opposing surfaces,

wherein webs (9) are provided on one of the two surfaces of the elongate component (8), which are arranged and designed so that they engage or can be inserted into the corresponding recesses (7) of the circuit card (2).

4. Apparatus according to claim 3,

wherein at least one stop support (10) for the printed circuit card (2) is provided on the elongated component (8) on the surface on which the webs (9) are arranged, the stop support (10) being designed so that the surface the elongated component (8), which carries the webs (9), has a defined distance from the facing surface of the printed circuit board (2).

5. Apparatus according to claim 3 or 4,

wherein at least one of the webs (9) in an area adjoining the surface of the elongate component (8) as a stop support (10) for the

Printed circuit board (2) is designed so that the surface of the elongated

Component (8), which carries the webs (9), has the defined distance from the facing surface of the printed circuit card (2).

6. The device according to one or more of the preceding claims, that the two in the end regions of the elongate component (8) arranged webs (9) each in the web region that is in the

corresponding recess protrudes, are designed as snap hooks (11) in such a way that the elongate component (8) can be fixed, preferably detachably, on the circuit board (2).

7. Device according to at least one of claims 3-6,

wherein the width (b) of the recesses (7) and webs (9) is designed so that the creepage distance on the circuit board (2) around a recess (7) or around a web (9) to comply with the specified

Type of protection is sufficient.

8. Device according to at least one of claims 3-6,

wherein the height (h) of the webs (9) is designed so that the creepage distance along the webs (9) is sufficient to maintain the specified type of protection.

9. Device according to one or more of claims 3-8,

wherein the elongated component (8) with webs (9), snap hooks (11) and stop supports (10, 10a) is made of a non-conductive material, flexible material, preferably plastic.

10. Apparatus according to claim 1,

where the type of protection is preferably Ex ec - increased safety.